fix(llc): handle per-channel notification.mark_read events again

[xsahil03x]

Linear: FLU-693
Github Issue: #2886

CLA

• I have signed the Stream CLA (required).
• The code changes follow best practices
• Code changes are tested

Description of the pull request

ChannelClientState._listenReadEvents subscribed to both message.read and notification.mark_read until the delivery-receipts refactor (#2429, 3b5e410bb) split them into separate listeners and did not carry notification.mark_read over. The changelog documents the rest of that refactor but not this removal, so it looks unintentional.

That distinction is load-bearing:

• message.read is a channel event — delivered to watchers only.
• notification.mark_read is delivered on the reading user's own connection — so it reached the channel whether watched or not.

Channel.markRead() writes no local state itself, and channels are easily non-watched (watch is silently downgraded when there is no connection id). So from 9.20.0 on, marking a non-watched channel as read succeeded server-side while unreadCount stayed stale forever — the unread pill and divider survived the dismiss X, markReadWhenAtTheBottom, and every reopen, with no user action able to clear them.

The fix re-adds the event type to the existing listener:

_channel.on(EventType.messageRead, EventType.notificationMarkRead).listen(

Not a literal revert. The handler has improved since 9.19.0 — it now skips thread-scoped reads and preserves lastDeliveredAt / lastDeliveredMessageId — and the merged listener keeps both. Nothing from #2429 is undone.

Verification against the backend event definition

Rather than infer the payload, I checked lib/chat/event/notification_mark_read.go. The two events are the same shape for every field the handler reads:

Handler reads	message.read	notification.mark_read
event.thread	thread,omitempty	thread,omitempty
event.user	yes	yes — non-nil at both emit sites
event.createdAt	yes	yes
event.lastReadMessageId	yes	yes
per-channel unread count	absent	absent

Which settles three things:

• unreadMessages: 0 is correct, not a compromise. unread_messages exists on exactly one event in the backend — notification.mark_unread. On notification.mark_read, unread_count / total_unread_count are account-wide totals, and unread_count is deprecated. Neither event can report this channel's count, so 0 is the only available value.
• No last_read_at, so lastRead: event.createdAt is right.
• The thread guard is load-bearing. NewNotificationMarkThreadReadEvent sets Thread, so thread mark-reads do arrive on this type and would otherwise clobber the channel-level Read.

Also confirmed: read_state.go returns early when !channel.Config.ReadEvents, so no event is emitted for read-events-disabled channel types — channels using local unread counts are unaffected. And markAllRead() posts {}, which routes to MarkAllRead → an event with no cid, exactly what the client-level handler's if (event.cid != null) return; expects. The channel-level / client-level split is correct.

Testing

Four tests in channel_test.dart. I verified they actually catch the regression by reverting the one-line fix and re-running — three go red:

Test	Without the fix
resets unread count on a non-watched channel	fails: Expected: <0> Actual: <10>
preserves delivery info	fails: Expected: <0> Actual: <10>
reconciles delivery for the current user	fails: No matching calls
ignores thread-scoped mark-reads	passes (negative test, guards the guard)

Full stream_chat suite: 1624 passing. dart analyze --fatal-infos and dart format clean.

Out of scope

• Client-level counters are not broken on master. The issue reports totalUnreadCount / unreadChannels going stale too, and the reporter shipped a client-level listener for it. That part isn't needed — ClientState.subscribeToEvents applies both from any event carrying them, and set currentUser pumps them through _computeUnreadCounts.
• Persistence package causes double unread count to appear in scroll to bottom button and no unread count on the back button when opened from message notification #2202 (reconnect sync() replay re-incrementing unreadCount via the non-idempotent addNewMessage) is real and related — through 9.19.0 this reset washed that drift away on the next mark-read — but it's a separate bug.
• Test-coverage gap worth its own PR: 10 other event subscriptions in channel.dart have zero test references anywhere in the suite, so any could be silently dropped the same way with CI staying green — channel.truncated, notification.channel_truncated, channel.updated, member.added, member.removed, user.banned, user.unbanned, reaction.updated, poll.closed, poll.updated. Tracked in FLU-693's notes.

Screenshots / Videos

Not applicable — no visual change beyond the unread pill and divider now clearing, which is the bug itself.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Fixed unread counts and read-state updates when marking a channel as read while not actively viewing it.
  • Preserved delivery information and correctly handled read events, including current-user updates.
  • Ignored thread-specific read notifications when updating channel-level state.

• Tests

  • Added coverage for unread counts, read states, delivery details, and thread-scoped notifications.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 3923f914-24ca-4eea-8c42-850a86aa58cb

📥 Commits

Reviewing files that changed from the base of the PR and between cb43fc4 and a9b0482.

📒 Files selected for processing (3)

• packages/stream_chat/CHANGELOG.md
• packages/stream_chat/lib/src/client/channel.dart
• packages/stream_chat/test/src/client/channel_test.dart

---

📝 Walkthrough

Walkthrough

The channel read-event listener now handles notification.mark_read events. Tests cover channel and thread read state, unread counts, delivery metadata, and current-user delivery reconciliation. The changelog documents the fix.

Changes

Notification mark-read handling

Layer / File(s)	Summary
Read-event handling packages/stream_chat/lib/src/client/channel.dart, packages/stream_chat/CHANGELOG.md	The listener processes notification.mark_read alongside message.read and applies the existing read-state updates and delivery reconciliation.
Read-state validation packages/stream_chat/test/src/client/channel_test.dart	Tests cover unread-count resets, delivery metadata preservation, thread-scoped events, and current-user delivery reconciliation.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to a9b04

This is a localized fix that restores per-channel read notifications and is covered by targeted tests; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: testableapple

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the restored handling of per-channel notification.mark_read events.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/notification-mark-read-unread-count

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.96%. Comparing base (cb43fc4) to head (ecbe969).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2890   +/-   ##
=======================================
  Coverage   73.96%   73.96%           
=======================================
  Files         435      435           
  Lines       28149    28149           
=======================================
  Hits        20821    20821           
  Misses       7328     7328           

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